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1.
Osteoarthritis Cartilage ; 30(4): 559-569, 2022 04.
Artículo en Inglés | MEDLINE | ID: mdl-35031493

RESUMEN

OBJECTIVE: Proton pump inhibitors (PPIs) are among the most commonly used medications for patients with osteoarthritis (OA). Various types of PPIs have different impacts on lowering serum magnesium level that may affect knee OA progression. We aimed to compare the risk of clinically relevant endpoint of knee replacement (KR) among initiators of five different PPIs with that among histamine-2 receptor antagonist (H2RA) initiators. DESIGN: Among patients with knee OA (≥50 years) in The Health Improvement Network database in the UK we conducted five sequential propensity-score matched cohort studies to compare the risk of KR over 5-year among patients who initiated omeprazole (n = 2,672), pantoprazole (n = 664), lansoprazole (n = 3,747), rabeprazole (n = 751), or esomeprazole (n = 827) with those who initiated H2RA. RESULTS: The prevalence of PPI prescriptions among participants with knee OA increased from 12.7% in 2000-44.0% in 2017. Two-hundred-and-seventy-four KRs (30.8/1,000 person-years) occurred in omeprazole initiators and 230 KRs (25.4/1,000 person-years) in H2RA initiators. Compared with H2RA initiators, the risk of KR was 21% higher in omeprazole initiators (hazard ratio [HR] = 1.21,95% confidence interval [CI]:1.01-1.44). Similar results were observed when pantoprazole use was compared with H2RA use (HR = 1.38,95%CI:1.00-1.90). No such an increased risk of KR was observed among lansoprazole (HR = 1.06,95%CI:0.92-1.23), rabeprazole (HR = 0.97,95%CI:0.73-1.30), or esomeprazole (HR = 0.83,95%CI:0.60-1.15) initiators compared with that among H2RA initiators. CONCLUSIONS: In this population-based cohort study, initiation of omeprazole or pantoprazole use was associated with a higher risk of KR than initiation of H2RA use. This study raises concern regarding an unexpected risk of omeprazole and pantoprazole on accelerating OA progression.


Asunto(s)
Osteoartritis de la Rodilla , Inhibidores de la Bomba de Protones , Estudios de Cohortes , Esomeprazol , Humanos , Lansoprazol/uso terapéutico , Omeprazol/farmacología , Omeprazol/uso terapéutico , Osteoartritis de la Rodilla/tratamiento farmacológico , Pantoprazol/uso terapéutico , Inhibidores de la Bomba de Protones/efectos adversos , Rabeprazol
2.
Osteoarthritis Cartilage ; 30(10): 1337-1343, 2022 10.
Artículo en Inglés | MEDLINE | ID: mdl-35863678

RESUMEN

INTRODUCTION: Higher intake of fiber has been associated with lower risk of incident symptomatic osteoarthritis (OA). We examined whether levels of alkylresorcinol (AR), a marker of whole grain intake, were associated with OA in subjects in The Multicenter Osteoarthritis (MOST) Study. METHOD: Knee x-rays and knee pain were assessed at baseline and through 60-months. Stored baseline fasting plasma samples were analyzed for AR homologues (C17:0, C19:0, C21:0, C23:0, C25:0) and total AR levels (AR sum). Two nested case-control studies, one for incident radiographic OA and one for incident symptomatic OA were performed with participants re-assessed at 15, 30 and 60 months. Multivariable conditional logistic regression with baseline covariates including age, sex, BMI, physical activity, quadriceps strength, race, smoking, depressive symptoms, diabetes and knee injury tested the association of log transformed AR levels with OA outcomes. RESULTS: Seven hundred seventy-seven subjects were, on average, in their 60's, and most were women. For 60-month cumulative incidence, there was no significant association between quartiles of AR concentration and incident radiographic (e.g., for incident radiographic OA, highest vs lowest quartile of AR sum showed RR = 0.93 (95% CI 0.59, 1.47), and for symptomatic OA RR was 1.22 (95% CI 0.76, 1.94). In secondary analyses examining 30-month incidence, high AR levels were associated with a reduced risk of X-ray OA (RR = 0.31 (95% CI 0.15, 0.64). CONCLUSION: In primary analyses, AR levels were not associated with risk of OA, but secondary analyses left open the possibility that high AR levels may protect against OA.


Asunto(s)
Osteoartritis de la Rodilla , Osteoartritis , Biomarcadores , Femenino , Humanos , Imidazoles , Articulación de la Rodilla , Masculino , Osteoartritis/complicaciones , Osteoartritis de la Rodilla/diagnóstico por imagen , Osteoartritis de la Rodilla/epidemiología , Osteoartritis de la Rodilla/etiología , Sulfonamidas , Tiofenos , Granos Enteros
3.
Osteoarthritis Cartilage ; 29(7): 973-978, 2021 07.
Artículo en Inglés | MEDLINE | ID: mdl-33757857

RESUMEN

OBJECTIVE: Inflammation worsens joint destruction in osteoarthritis (OA) and aggravates pain. Saturated and n-6 fatty acids (FAs) increase, whereas n-3 FAs reduce inflammation. We examined whether FA levels affected the development of OA. DESIGN: We studied participants from the Multicenter Osteoarthritis study (MOST) at risk of developing knee OA. After baseline, repeated knee x-rays and MRIs were obtained and knee symptoms queried through 60 month follow-up. Using baseline fasting samples, serum FAs were analyzed with standard assays. After excluding participants with baseline OA, we defined two sets of cases: those developing radiographic OA and those developing symptomatic OA (knee pain and radiographic OA). Controls did not develop these outcomes. Additionally, we examined worsening of MRI cartilage loss and synovitis and of knee pain using WOMAC and evaluated the number of hand joints affected by nodules. In regression models, we tested the association of each OA outcome with levels of saturated, n-3 and n-6 FAs adjusting for age, sex, BMI, education, race, baseline pain and depressive symptoms. RESULTS: We studied 260 cases with incident symptomatic and 259 with incident radiographic OA. Mean age was 61 years (61% women). We found no signficant nor suggestive associations of FA levels with incident OA (e.g., for incident symptomatic OA, OR per s.d. increase in n-3 FA 1.00 (0.85, 1.18) nor with any OA outcome in knee or hand. CONCLUSION: Despite previously described effects on systemic inflammation, blood levels of FAs were not associated with risk of later knee OA or other OA outcomes.


Asunto(s)
Ácidos Grasos/sangre , Osteoartritis de la Rodilla/diagnóstico por imagen , Anciano , Femenino , Humanos , Estudios Longitudinales , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Rayos X
4.
Osteoarthritis Cartilage ; 27(10): 1454-1461, 2019 10.
Artículo en Inglés | MEDLINE | ID: mdl-31181261

RESUMEN

OBJECTIVE: Thiazide diuretic use is associated with higher bone mineral density (BMD) and possibly lower serum magnesium levels than loop diuretic use, and both high BMD and low serum magnesium have been linked to high prevalent knee osteoarthritis. This study aimed to compare the risk of a clinically relevant endpoint, knee replacement (KR) surgery, among initiators of thiazide and loop diuretics. DESIGN: Among patients aged ≥50 years with a diagnosis of knee osteoarthritis in The Health Improvement Network (THIN) in United Kingdom, we conducted a propensity score-matched cohort study to examine the relation of thiazide diuretic initiation vs loop diuretic initiation to the risk of KR over 5 years. RESULTS: Among thiazide and loop diuretic initiators (n = 3,488 for each group; mean age: 73 years; female ratio: 59%), 359 (28.6/1,000 person-years) and 283 (24.1/1,000 person-years) KRs occurred during the follow-up period, respectively. The hazard ratio (HR) of KR for thiazide diuretic initiation vs loop diuretic initiation was 1.26 (95% confidence interval [CI]: 1.08-1.47). The adherence-adjusted HR of KR for continuous use of thiazide diuretics was 1.44 (95% CI: 1.21-1.72). CONCLUSIONS: In this population-based cohort of patients with knee osteoarthritis, thiazide diuretic use was associated with a higher risk of KR than loop diuretic use. This association may potentially be due to thiazide diuretics' effect on BMD and serum magnesium.


Asunto(s)
Artroplastia de Reemplazo de Rodilla/estadística & datos numéricos , Osteoartritis de la Rodilla/cirugía , Inhibidores de los Simportadores del Cloruro de Sodio/efectos adversos , Inhibidores del Simportador de Cloruro Sódico y Cloruro Potásico/efectos adversos , Anciano , Estudios de Cohortes , Femenino , Humanos , Masculino , Puntaje de Propensión , Medición de Riesgo , Factores de Riesgo
5.
Clin Exp Immunol ; 187(3): 369-375, 2017 03.
Artículo en Inglés | MEDLINE | ID: mdl-27783394

RESUMEN

NKG2D (KLRK1) is a C-type lectin receptor present on natural killer (NK) cells, γδ, CD8+ and CD4+ T cells. Upon ligand binding, NKG2D mediates activatory and co-stimulatory signals to NK cells and activated CD4+ T cells, respectively. Polymorphisms in NKG2D predispose to infectious diseases, cancer, transplantation and autoimmune disorders. We studied the influence of this NK receptor polymorphism on predisposition to and modification of the disease phenotype in patients with rheumatoid arthritis (RA). Eight different single nucleotide polymorphisms (SNP) in the NKG2 gene were genotyped in 236 patients with RA and 187 controls using Taqman 5' nuclease assays. NKG2D genotype/allele frequency did not differ between patients and controls. Subgroup analysis showed that the frequency of A allele of NKG2D9 and T allele of NKG2D10 was significantly higher in patients with deformities (a marker of severe disease) [11 versus 5%, Pc = 0·03, odds ratio (OR) = 2·44, 95% confidence interval (CI) = 1·09-5·98 and 10 versus 4%, Pc = 0·04, OR = 2·45, 95% CI = 1·05-6·39, respectively], while the frequency of alleles G of NKG2D9 and A of NKG2D10 was greater in patients without deformities (Pc = 0·03, OR = 0·41, 95% CI = 0·17-0·91 and Pc = 0·04, OR = 0·41, 95% CI = 0·16-0·96). Similar trends of association were observed with deforming phenotype of RA in female patients and deforming young onset RA subgroups. Haplotype analysis revealed that the frequency of haplotype G-C-A-G-A-T-C-C was higher in patients than in controls (12 versus 8%, P = 0·04, OR = 1·61, 95% CI = 1·01-2·55), suggesting that it may predispose to RA. Our study suggests that the NKG2D gene polymorphisms may modify the risk of development and severity of RA.


Asunto(s)
Artritis Reumatoide/genética , Predisposición Genética a la Enfermedad/genética , Subfamilia K de Receptores Similares a Lectina de Células NK/genética , Polimorfismo de Nucleótido Simple/genética , Adolescente , Adulto , Anciano , Alelos , Estudios de Casos y Controles , Femenino , Frecuencia de los Genes/genética , Haplotipos/genética , Humanos , Lectinas Tipo C , Masculino , Persona de Mediana Edad , Oportunidad Relativa , Adulto Joven
6.
Int J Immunogenet ; 44(3): 114-121, 2017 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-28374504

RESUMEN

Nitric oxide synthase (NOS) catalyses the production of nitric oxide (NO) from L-Arginine, which participates in diverse biological processes including inflammation and apoptosis. Macrophages, chondrocytes, osteoblasts and osteoclasts express inducible NOS (iNOS) at the site of synovial inflammation. NO produced at the inflamed joint may contribute to peri-articular bone loss, mediate apoptosis and regulate Th1/Th2 balance in rheumatoid arthritis (RA). Variations in the promoter region of NOS gene regulate the nitric oxide synthase expression and iNOS (NOS2) polymorphisms have been associated with susceptibility to autoimmune disorders. Hence, this study was conducted to identify the possible contributions of NOS2 -1659G/A, -1026C/A, -277A/G promoter polymorphisms towards development of RA in South Indian Tamils. A total of 242 (219 females, 23 males) patients with RA (mean age 41.2 ± 10.9 years, disease duration 8.5 ± 4.3 years) and 279 age- and sex-matched healthy individuals of South Indian Tamil ethnicity were genotyped for NOS2 -1659C/T, -1026G/T and -277A/G promoter polymorphisms by TaqMan chemistry. Nature of disease (erosive or nonerosive), the presence of extra-articular manifestations, seropositivity for rheumatoid factor and anticyclic citrullinated peptide, serum C-reactive protein (CRP) level and response to therapy were assessed for all patients. The three single nucleotide polymorphisms (SNPs) were in Hardy-Weinberg equilibrium. The frequency of GG genotype and G allele of NOS2-277 was higher in patients (pc = 5.7 × 10-9 , OR = 6.09, 95% CI = 3.09-12.8 and pc = 4 × 10-13 , OR = 2.37, 95% CI = 2.06-3.62, respectively) compared to controls. Similarly, the frequency of NOS2-1026 (rs2779249) GT genotype and the T allele was higher in patients with RA (pc = .01, OR = 1.61, 95% CI = 1.09-2.36, and pc = .04, OR = 1.40, 95% CI = 1.02-1.91, respectively). However, no significant difference in frequency of NOS2-1659C/T polymorphism was observed between patients and controls. None of the studied SNPs were associated with erosive disease, seropositivity or extra-articular manifestations. The -277A/G and -1026 G/T promoter polymorphisms in iNOS may confer susceptibility to RA in South Indian Tamils.


Asunto(s)
Artritis Reumatoide/genética , Predisposición Genética a la Enfermedad , Óxido Nítrico Sintasa de Tipo II/genética , Regiones Promotoras Genéticas , Adolescente , Adulto , Anciano , Alelos , Artritis Reumatoide/metabolismo , Artritis Reumatoide/patología , Proteína C-Reactiva , Femenino , Estudios de Asociación Genética , Genotipo , Humanos , India , Masculino , Persona de Mediana Edad , Óxido Nítrico/metabolismo , Polimorfismo de Nucleótido Simple
7.
Phys Chem Chem Phys ; 18(8): 6191-200, 2016 Feb 17.
Artículo en Inglés | MEDLINE | ID: mdl-26852729

RESUMEN

Zintl compounds are potential candidates for efficient thermoelectric materials, because typically they are small band gap semiconductors. In addition, such compounds allow fine tuning of the carrier concentration by chemical doping for the optimization of thermoelectric performance. Herein, such tunability is demonstrated in Mg3Sb2-based Zintl compounds via Zn(2+) doping at the Mg(2+) site of the anionic framework (Mg2Sb2)(2-), in the series Mg3-xZnxSb2 (0 ≤ x ≤ 0.1). The materials have been successfully synthesized using the spark plasma sintering (SPS) technique. X-ray diffraction (XRD) analysis confirms a single solid solution phase of Mg3-xZnxSb2 (0 ≤ x ≤ 0.1). The thermoelectric properties are characterized by the Seebeck coefficient, electrical conductivity, and thermal conductivity measurements from 323 K to 773 K. Isoelectronic Zn substitution at the Mg site presents the controlled variation in the carrier concentration for optimizing the high power factor and reduced thermal conductivity. These results lead to a substantial increase in ZT of 0.37 at 773 K for a composition with x = 0.10 which is ∼42% higher than undoped Mg3Sb2. The electronic transport data for the Mg3-xZnxSb2 (0 ≤ x ≤ 0.1) compound are analyzed using a single parabolic band model predicting that Mg2.9Zn0.1Sb2 exhibits a near-optimal carrier concentration for high ZT. The electronic structure of transport properties of these disordered Mg3-xZnxSb2 (0 ≤ x ≤ 0.1) is also studied using density functional theory and the results obtained are in good agreement with experimental results. The low cost, lightness and non-toxicity of the constituent elements make these materials ideal for mid-temperature thermoelectric applications.

8.
Z Rheumatol ; 75(2): 200-2, 2016 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-26555550

RESUMEN

Rheumatoid vasculitis usually occurs on the background of seropositive rheumatoid arthritis, although in rare cases the patients can be seronegative. We report a woman with seronegative rheumatoid arthritis with rheumatoid vasculitis who developed toxic epidermal necrolysis involving most of her body surface area, while on therapy with intravenous cyclophosphamide and mesna. After withdrawal of suspected offending agents, administration of intravenous immunoglobulin, and supportive therapy, she had a favorable outcome. Such an occurrence is rare and serves to educate about a potentially life-threatening adverse event associated with a commonly used immunosuppressive agent.


Asunto(s)
Ciclofosfamida/efectos adversos , Mesna/efectos adversos , Vasculitis Reumatoide/tratamiento farmacológico , Síndrome de Stevens-Johnson/diagnóstico , Síndrome de Stevens-Johnson/etiología , Síndrome de Stevens-Johnson/terapia , Antirreumáticos/efectos adversos , Antirreumáticos/uso terapéutico , Artritis Reumatoide/sangre , Artritis Reumatoide/tratamiento farmacológico , Ciclofosfamida/uso terapéutico , Humanos , Mesna/uso terapéutico , Sustancias Protectoras/efectos adversos , Sustancias Protectoras/uso terapéutico , Vasculitis Reumatoide/sangre , Resultado del Tratamiento
9.
Osteoarthritis Cartilage ; 23(2): 244-8, 2015 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-25451303

RESUMEN

OBJECTIVE: Role of intra-articular calcium crystals in osteoarthritis (OA) is unclear. Imaging modalities used to date for its evaluation have limitations in their ability to fully characterize intra-articular crystal deposition. Since Computed Tomography (CT) imaging provides excellent visualization of bones and calcified tissue, in this pilot project we evaluated the utility of CT scan in describing intra-articular calcium crystal deposition in the knees. METHOD: We included 12 subjects with and four subjects without radiographic chondrocalcinosis in the most recent visit from the Multicenter Osteoarthritis (MOST) study, which is a longitudinal cohort of community-dwelling older adults with or at risk for knee OA. All subjects underwent CT scans of bilateral knees. Each knee was divided into 25 subregions and each subregion was read for presence of calcium crystals by a musculoskeletal radiologist. To assess reliability, readings were repeated 4 weeks later. RESULTS: CT images permitted visualization of 25 subregions with calcification within and around the tibio-femoral and patello-femoral joints in all 24 knees with radiographic chondrocalcinosis. Intra-articular calcification was seen universally including meniscal cartilage (most common site involved in 21/24 knees), hyaline cartilage, cruciate ligaments, medial collateral ligament and joint capsule. Readings showed good agreement for specific tissues involved with calcium deposition (kappa: 0.70, 95% CI 0.62-0.80). CONCLUSION: We found CT scan to be a useful and reliable tool for describing calcium crystal deposition in the knee and therefore potentially for studying role of calcium crystals in OA. We also confirmed that "chondrocalcinosis" is a misnomer because calcification is present ubiquitously.


Asunto(s)
Calcio/metabolismo , Condrocalcinosis/diagnóstico por imagen , Condrocalcinosis/metabolismo , Articulación de la Rodilla/metabolismo , Tomografía Computarizada por Rayos X , Anciano , Cristalización , Femenino , Humanos , Masculino , Persona de Mediana Edad , Proyectos Piloto
10.
Lupus ; 24(9): 994-7, 2015 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-25661833

RESUMEN

Subarachnoid hemorrhage and dural sinus thrombosis are important manifestations of neuropsychiatric lupus erythematosus. We report the case of a woman with relapsed lupus nephritis, in partial remission, who presented with the unusual combination of dural sinus thrombosis (due to protein S functional deficiency) and aneurysmal subarachnoid hemorrhage. She had a fatal outcome, as has often been reported with subarachnoid hemorrhage in the context of active lupus. To our knowledge, this is the first report of such an unusual association in lupus, and highlights unique challenges in the management of intracranial hemorrhage in the context of dural sinus thrombosis.


Asunto(s)
Nefritis Lúpica/complicaciones , Vasculitis por Lupus del Sistema Nervioso Central/complicaciones , Trombosis de los Senos Intracraneales/complicaciones , Hemorragia Subaracnoidea/complicaciones , Adulto , Biopsia , Resultado Fatal , Femenino , Humanos , Nefritis Lúpica/patología , Vasculitis por Lupus del Sistema Nervioso Central/patología , Recurrencia , Tomografía Computarizada por Rayos X
11.
Phys Chem Chem Phys ; 17(44): 30090-101, 2015 Nov 28.
Artículo en Inglés | MEDLINE | ID: mdl-26499748

RESUMEN

All scale hierarchical architecturing, matrix/inclusion band alignment and intra-matrix electronic structure engineering, the so called panoscopic approach for thermoelectric materials has been demonstrated to be an effective paradigm for optimizing high ZT. To achieve such hierarchically organized microstructures, composition engineering has been considered to be an efficient strategy. In this work, such a panoscopic concept has been extended to demonstrate for the first time in the case of half-Heusler based thermoelectric materials via a composition engineering route. A series of new off-stoichiometric n-type Zr0.7Hf0.3Ni1+xSn (0 ≤x≤ 0.10) HH compositions have been modified to derive HH(1 -x)/full-Heusler (FH)(x) composite with an all scale hierarchically modified microstructure with FH inclusions within the matrix to study the temperature dependent thermoelectric properties. The structural analysis employing XRD, FE-SEM and HR-TEM of these materials reveal a composite of HH and FH, with hierarchically organized microstructures. In such a submicron/nano-composite, the electronic properties are observed to be well optimized yielding a large power factor; α(2)σ (∼30.7 × 10(-4) W m(-1) K(-2) for Zr0.7Hf0.3Ni1.03Sn) and reduced thermal conductivity (∼2.4 W m(-1) K(-1) for Zr0.7Hf0.3Ni1.03Sn) yielding a high ZT∼ 0.96 at 773 K for composition Zr0.7Hf0.3Ni1.03Sn which is ∼250% larger than the normal HH Zr0.7Hf0.3NiSn (ZT∼ 0.27 at 773 K). The enhancement in ZT of these composites has been discussed in terms of primary electron filtering, electron injection and several phonon scattering mechanisms such as alloy scattering, point defect scattering, and grain boundary scattering. The Bergman and Fel model is used to calculate effective thermoelectric parameters of these composites for comparing the experimental results.

12.
13.
Osteoporos Int ; 25(6): 1677-84, 2014 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-24833176

RESUMEN

UNLABELLED: Association between warfarin use and fracture risk is unclear. We examined the association between long-term warfarin use and fracture risk at the hip, spine, and wrist in elders. No significant association was found between long-term warfarin use and fracture risk, despite biological plausibility. INTRODUCTION: Prior studies examining the association of warfarin use and osteoporotic fractures have been conflicting, potentially related to methodological limitations. Thus, we examined the association of long-term warfarin use with risk of hip, spine, and wrist fractures among older adults with atrial fibrillation, attempting to address prior methodologic challenges. METHODS: We included men and women ≥ 65 years of age with incident atrial fibrillation and without prior history of fractures from The Health Improvement Network followed between 2000 and 2010. Long-term warfarin use was defined in two ways: (1) warfarin use ≥ 1 year; (2) warfarin use ≥ 3 years. Propensity-score matched cohorts of warfarin users and nonusers were created to evaluate the association between long-term warfarin use and risk of hip, spine, and wrist fractures separately as well as combined, using Cox-proportional hazards regression models. RESULTS: Among >20,000 participants with incident atrial fibrillation, the hazard ratios (HR) for hip fracture with warfarin use ≥ 1 and ≥ 3 years, respectively, were 1.08 (95%CI 0.87, 1.35) and 1.13 (95% CI 0.84, 1.50). Similarly, no significant associations were observed between long-term warfarin use and risk of spine or wrist fracture. When risk of any fracture was assessed with warfarin use, no association was found [HR for warfarin use ≥ 1 year 0.92 (95%CI 0.77, 1.10); HR for warfarin use ≥ 3 years 1.12 (95%CI 0.88, 1.43)]. CONCLUSIONS: Long-term warfarin use among elders with atrial fibrillation was not associated with increased risk of osteoporotic fractures and therefore does not appear to necessitate additional surveillance or prophylaxis.


Asunto(s)
Anticoagulantes/efectos adversos , Fibrilación Atrial/tratamiento farmacológico , Fracturas Osteoporóticas/inducido químicamente , Warfarina/efectos adversos , Anciano , Anciano de 80 o más Años , Anticoagulantes/administración & dosificación , Anticoagulantes/uso terapéutico , Fibrilación Atrial/epidemiología , Bases de Datos Factuales , Esquema de Medicación , Utilización de Medicamentos/estadística & datos numéricos , Femenino , Fracturas de Cadera/inducido químicamente , Fracturas de Cadera/epidemiología , Humanos , Incidencia , Masculino , Fracturas Osteoporóticas/epidemiología , Puntaje de Propensión , Medición de Riesgo/métodos , Fracturas de la Columna Vertebral/inducido químicamente , Fracturas de la Columna Vertebral/epidemiología , Reino Unido/epidemiología , Warfarina/administración & dosificación , Warfarina/uso terapéutico , Traumatismos de la Muñeca/inducido químicamente , Traumatismos de la Muñeca/epidemiología
14.
Phys Rev Lett ; 111(24): 243201, 2013 Dec 13.
Artículo en Inglés | MEDLINE | ID: mdl-24483657

RESUMEN

We present an experimental determination of the 2p3d(1Po)→1s3d(1De) x-ray line emitted from He-like Si, S, and Cl projectile ions, excited in collisions with thin carbon foils, using a high-resolution bent-crystal spectrometer. A good agreement between the observation and state-of-the-art relativistic calculations using the multiconfiguration Dirac-Fock formalism including the Breit interaction and QED effects implies the dominance of fluorescent decay over the autoionization process for the 2p3d(^{1}P^{o}) state of He-like heavy ions. This is the first observation of the fluorescence-active doubly excited states in He-like Si, S, and Cl ions.

15.
Nanotechnology ; 24(18): 185201, 2013 May 10.
Artículo en Inglés | MEDLINE | ID: mdl-23575106

RESUMEN

We nominate the nickel filled multiwalled carbon nanotubes (MWNTs) as potential candidates to cope with challenges in persistent scaling for future interconnect technology. The insights into electrical transport through nickel filled carbon nanotubes provide an effective solution for major performance and reliability issues such as the increasing resistivity of metals at reduced scales, electromigration at high current densities and the problem of diffusion and corrosion faced by the existing copper interconnect technology. Furthermore, the nickel filled MWNTs outperform their hollow counterparts, the unfilled MWNTs, carrying at least one order higher current density, with increased time to failure. The results suggest that metal filled carbon nanotubes can provide a twofold benefit: (1) the metal filling provides an increased density of states for the system leading to a higher current density compared to hollow MWNTs, (2) metal out-diffusion and corrosion is prevented by the surrounding graphitic walls.

16.
Pediatr Surg Int ; 29(5): 511-7, 2013 May.
Artículo en Inglés | MEDLINE | ID: mdl-23417523

RESUMEN

AIM: To review our practice of Meckel's Tc-99m pertechnetate scans over 18 years with regard to indications for the test, sensitivity and specificity in our particular referral patients' population. MATERIALS AND METHODS: This is a retrospective review of Meckel's scans performed in two paediatric tertiary care teaching hospitals from April 1993 to March 2011 and followed up till October 2011. The scan was performed according to published international guidelines. 183 patients were included in this study. We classified the patients into two groups: group 1, which included 77 patients (42 %) presenting with painless per rectum bleeding, and group 2, which included 106 patients (58 %) presenting with other non-specific symptoms (e.g. abdominal pain, possibly associated with nausea and/or vomiting, failure to thrive). Data were analysed using Chi square test, considering P value less than 0.05 as significant. The age of the patients ranged from 4 days to 16.5 years (median 3 years). RESULTS: 161 of the total 183 children on the study (88 %) had a negative Meckel's scan, and 22 children (12 %) had a positive scan. In the group with a positive Meckel's scan (22 children), all patients underwent surgical exploration and ectopic gastric mucosa was found in 17 cases (77 %, true positives). In the remaining 5 cases (23 %), there was no evidence of ectopic gastric mucosa (false positives). Within the group with a negative scan, 8 children (5 %) underwent surgery; only 1 child had a ectopic gastric mucosa detected following surgery (false negative). In other 52 children (32 %) of the group with a negative Meckel's scan, an endoscopy was done, which showed a normal result in 21 children and was abnormal in 31 children. Of the remaining 101 (63 %) children with a negative Meckel's scan, 74 children (46 %) improved without any further intervention. In 13 cases (8 %), other pathologies were identified. The sensitivity and specificity of the Meckel's scan for ectopic gastric mucosa were 94 and 97 %, respectively. The Meckel's scan was positive in 26 % of the patients of group 1 and in only 2 % patients of group 2. The difference between the two groups was highly significant [P < 0.0001 (Yates-corrected Chi square); odds ratio 18 (Woolf-logit method 95 % CI)]. CONCLUSION: The Meckel's scan retains a high diagnostic accuracy in children for detecting a Meckel's diverticulum with ectopic gastric mucosa within it, when performed according to the recommended guidelines. The test yields its highest positive result in children presenting with significant per rectum bleeding.


Asunto(s)
Divertículo Ileal/diagnóstico por imagen , Adolescente , Niño , Preescolar , Coristoma/diagnóstico por imagen , Femenino , Mucosa Gástrica , Humanos , Lactante , Recién Nacido , Masculino , Divertículo Ileal/cirugía , Cintigrafía , Estudios Retrospectivos , Sensibilidad y Especificidad
17.
Phys Rev Lett ; 109(11): 113202, 2012 Sep 14.
Artículo en Inglés | MEDLINE | ID: mdl-23005625

RESUMEN

We present a novel experimental tool allowing for kinematically complete studies of break-up processes of laser-cooled atoms. This apparatus, the 'MOTReMi,' is a combination of a magneto-optical trap (MOT) and a reaction microscope (ReMi). Operated in an ion-storage ring, the new setup enables us to study the dynamics in swift ion-atom collisions on an unprecedented level of precision and detail. In the inaugural experiment on collisions with 1.5 MeV/amu O(8+)-Li the pure ionization of the valence electron as well as the ionization-excitation of the lithium target was investigated.

18.
Small ; 7(5): 688-93, 2011 Mar 07.
Artículo en Inglés | MEDLINE | ID: mdl-21302358

RESUMEN

The surface morphology of bucky papers (BPs) made from single-walled carbon nanotubes (CNTs) is modified by plasma treatment resulting in the formation of vertical microstructures on the surface. The shapes of these structures are either pillarlike or conelike depending on whether the gas used during plasma treatment is Ar or CH(4) . A complex interplay between different factors, such as the electric field within the plasma sheath, polarization of the CNT, intertubular cohesive forces, and ion bombardment, result in the formation of these structures. The roles played by these factors are quantitatively and qualitatively analyzed. The final material is flexible, substrate-free, composite-free, made only of CNTs, and has discrete vertically aligned structures on its surface. It shows enhanced field emission and electrochemical charge-storage capabilities. The field enhancement factor is increased by 6.8 times, and the turn-on field drops by 3.5 times from an initial value of 0.35 to 0.1 V µm(-1) as a result of the treatment. The increase in Brunauer-Emmett-Teller surface area results in about a fourfold improvement in the specific capacitance of the BP electrodes. Capacitance values before and after the treatments are 75 and 290 F g(-1) , respectively. It is predicted that this controlled surface modification technique could be put to good use in several applications based on macroscopic CNT films.


Asunto(s)
Nanotecnología/métodos , Nanotubos de Carbono/química , Electrodos , Microscopía Electrónica de Rastreo , Propiedades de Superficie
19.
Osteoporos Int ; 22(1): 345-9, 2011 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-20442986

RESUMEN

UNLABELLED: Association between dietary protein and fracture risk is unclear. We examined association between energy-adjusted protein intake and hip fracture risk in elders. The risk of hip fracture was reduced in upper quartiles of protein intake when compared with lowest quartile. INTRODUCTION: Studies of the association between dietary protein intake and hip fracture risk are conflicting. Therefore, we examined protein intake and hip fracture risk in a population-based group of elderly men and women. METHODS: Five hundred seventy-six women and 370 men from the Framingham Osteoporosis Study with no previous history of hip fracture completed Food Frequency Questionnaires. Energy-adjusted protein intake was evaluated as a continuous variable and as quartiles. Incidence rates and hazard ratios were calculated, adjusting for age, BMI, sex, and energy intake. RESULTS: Among 946 participants (mean age 75 years), mean protein intake was found to be 68 gm/d. Increased protein intake was associated with a decreased risk of hip fracture compared to those in the lowest quartile of protein intake (Q2 HR = 0.70, Q3 HR = 0.56, and Q4 HR = 0.63; all p values ≥ 0.044), p for trend was 0.07. When a threshold effect was considered (Q2-4 vs Q1), intakes in the higher quartiles combined were associated with a significantly lower risk for hip fracture (HR = 0.63; p = 0.04). CONCLUSION: Our results are consistent with reduced risk of hip fracture with higher dietary protein intake. Larger prospective studies are needed to confirm and extend this finding in elderly men and women.


Asunto(s)
Proteínas en la Dieta/administración & dosificación , Fracturas de Cadera/prevención & control , Fracturas Osteoporóticas/prevención & control , Anciano , Anciano de 80 o más Años , Dieta/estadística & datos numéricos , Métodos Epidemiológicos , Femenino , Fracturas de Cadera/epidemiología , Humanos , Masculino , Massachusetts/epidemiología , Fracturas Osteoporóticas/epidemiología
20.
Nanotechnology ; 22(22): 225606, 2011 Jun 03.
Artículo en Inglés | MEDLINE | ID: mdl-21454931

RESUMEN

Chemical vapour deposition (CVD) is emerging as a popular method for growing large-area graphene on metal substrates. For transferring graphene to other substrates the technique generally used involves deposition of a polymer support with subsequent etching of the metal substrate. Here we report a simpler one-step transfer process. Few-layer graphene (FLG) grown on a Cu substrate were transferred to a silanized wafer by just pressing them together. Hydrogen bonding between the hydroxyl group on FLG and the amine group on silane molecules facilitate the transfer.

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